1. Technical Field
The present invention relates to a housing structure and a power steering apparatus.
2. Background Art
A conventional example of a housing structure for an electric power steering apparatus is described in Japanese Patent Application Laid-open No. H10-236322. Japanese Patent Application Laid-open No. H10-236322 describes a housing divided into a gear case (first housing) that houses a worm gear structure and that bears one end of an assist shaft such that the assist shaft is rotatable and a gear box (second housing) that houses a rack shaft meshing with a pinion on the assist shaft and that bears the other end of the assist shaft such that the assist shaft is rotatable. A fitting outer tubular portion is formed on the first housing, and a fitting inner tubular portion is formed on the second housing. The first housing and the second housing are integrated together by fitting the fitting inner tubular portion inside the fitting outer tubular portion and fastening the first housing and the second housing together using bolts. An outer tubular end surface (a surface orthogonal to the axis of the assist shaft) at a tip of the fitting outer tubular portion is brought into abutting contact with an outer tubular opposite surface of the second housing formed radially outside the fitting inner tubular portion. An O ring is interposed between the fitting inner tubular portion and the fitting outer tubular portion in order to seal the inside of the housings.